Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é a nacionalidade de Henry Carr tendo um tempo de 20.3 anos?
 ###Tabelas: CREATE TABLE 2009_draft_picks (2009_draft_picks_id AUTO_INCREMENT PRIMARY KEY, Round INT, Player VARCHAR, Position VARCHAR, Nationality VARCHAR, College/junior/club team (league) VARCHAR) CREATE TABLE current_members_of_the_howard_county_delegation (current_members_of_the_howard_county_delegation_id AUTO_INCREMENT PRIMARY KEY, District VARCHAR, Counties Represented VARCHAR, Delegate VARCHAR, Party VARCHAR, First Elected INT, Committee VARCHAR) CREATE TABLE records_1951–1976 (records_1951–1976_id AUTO_INCREMENT PRIMARY KEY, Time VARCHAR, Athlete VARCHAR, Nationality VARCHAR, Location of race VARCHAR, Date VARCHAR) CREATE TABLE bowling_averages_top_10 (bowling_averages_top_10_id AUTO_INCREMENT PRIMARY KEY, Player VARCHAR, Team VARCHAR, Matches INT, Overs VARCHAR, Wickets INT, Average VARCHAR, Economy VARCHAR, BBI VARCHAR, 4wi INT, 5wi INT) CREATE TABLE doubles:_9_4_titles_5_runner-ups (doubles:_9_4_titles_5_runner-ups_id AUTO_INCREMENT PRIMARY KEY, Outcome VARCHAR, Year VARCHAR, Tournament VARCHAR, Surface VARCHAR, Partnering VARCHAR, Opponents in the final VARCHAR, Score VARCHAR)  
SELECT Nationality FROM records_1951–1976 WHERE Athlete = henry carr AND Time = 20.3y